Device and method for producing respiration



Jan. 28, 1958 w. HOFMANN 2,821,

DEVICE AND METHOD FOR PRODUCING RESPIRATION Filed March 29, 1955 2 Shee'ts-Sheet 1 HECTMUE Alllllll /0 A52 INVENTOR.

#9172? fix-vva/m/ 0 BY /22@ M (MAUMPH DEVICE AND METHOD FOR PRODUCING RESPIRATION Filed March 29 1955 W. HOFMANN Jan. 28, 1958 2 Sheets-Sheet 2 Unite DEVICE AND IVETHQD FOR PRODUCING RESPIRATION Waiter Hofmaun, Tegernsee, Upper Bavaria, Germany, asslgnor, by mesne assignments, of seventy percent to rastel Qorporanon, Inc, Chicago, 111., a corporation Application March 29, 1955, Serial No. 497 ,747

Saints. (Cl. 128-29) This invention relates to a method and device for inducing artificial respiration and in a normal or predetermined breathing rhythm. This is a continuation-inpart of my copending application Serial No. 231,417, filed June 13, 1951, now Patent 2,711,729. The arrangement shown in the aforesaid appliaction provides means for the application of low frequency current impulses alternately to muscle groups controlling inspiration and muscle groups controlling expiration for the involuntary repetition of the breathing cycle where breathing has been immobilized by paralysis due, for example, to asthma, shock or similar causes. The device therein includes positive and negative electrodes in the form of a belt adapted for connection around the trunk of the body in the vicinity of the diaphragm. Low frequency current impulses passed through the body from the negative to the positive electrodes stimulates muscle groups which control inhalation. The exhalation phase is controlled by two single electrode belts, one connected below the arm pits and one connected at the abdomen whereby impulses are passed lengthwise of the body.

it is now found that the exhalation phase may be stimulated and controlled more advantageously by the use of a single two-electrode belt whereby low frequency current impulses are passed across the trunk of the body in the vicinity of the lower abdomen and preferably just below the navel.

An object of the invention is to stimulate the inspiratory phase of respiration by the application of current pulses alternately in breathing rhythm across the trunk of the body in the area of the diaphragm to inspiratory muscle groups and then across the trunk of the body in the area of the lower abdomen to expiratory muscle groups.

Another object of the invention is to provide an improved method and device for the alternate stimulation of inspiration and expiration automatically in any desired or required predetermined cycle.

A specific object of the invention is to provide a device in which the character, duration and magnitude of each stimulating pulse can be easily and accurately adjusted to the physiological requirements of the case, and in which the breathing rate as well as the duration of each inspiration and expiration phase can be controlled and adjusted asdesired.

Specific objects of the invention are the provision of an electro-respirator of this type in which duration of the actual electric pulses supplied to the several muscle groups during each inspiration and expiration phase may be varied independently of the duration of the inspiration or expiration phase itself, and in which an inspiration phase may be started immediately by the physician, or by the patient himself, at any stage of the automatic operation of the device.

These and other objects which will appear more clearly as the specification proceeds are accomplished by the method and apparatus described hereinafter in detail and defined in the appended claims.

According to the preferred embodiment of the invention, electric pulses are alternately supplied to at least one inspiratory muscle group by the application of positive and negative electrodes on opposite sides of the body in the area of the upper diaphragm and to at least one expiratory muscle group by the application of positive and negative electrodes on opposite sides of the body in the area of the abdomen, preferably the lower abdomen in the vicinity of the navel, and the alternate stimulation of the inspiratory and expiratory muscle groups by means of electric pulses is regulated in accordance with a predetermined breathing rhythm.

Applicant has discovered that passing low frequency current pulses transversely to the trunk of the body in the area of the lower abdomen stimulates the rectus abdominal muscle resulting in a contraction which forcibly produces expiration.

Apparatus for the execution of the method according to the present invention is illustratively exemplified in the appended drawings, in which:

Figure l is a diagram of the electrode circuits and the control circuits in one embodiment of an apparatus according to the invention;

Figure 2 is a circuit diagram of a timing device which may be used in combination with the electrode and control circuits according to Figure 1;

Figure 3 shows a wiring diagram using conventional symbols to illustrate the operation of relays S, R and C.

Figure 4 illustrates the application of the inspiratory and expiratory sets of electrodes to the human body.

Figure 5 illustrates an alternative method of applying the inspiratory and expiratory sets of electrodes to the body.

Figure 6 is a perspective view of the electrode belt section partly broken away and Figure 7 is a front view of the control box employed in the device described herein.

Referring now to the drawings, and first to Figures 1 to 3, the electro-respirator comprises two electrode circuits 19 and 20, each containing a triode valve 11 and 21, respectively. In each circuit 10 and 20, negative contact terminals N-10 and N20 are connected permanently to the anode of the associated triode through indicators 12, 22. The cathodes of the two valves are connected in parallel to the Zero potential of a source of current over a common conductor 30. The electrode circuits 10 and 2t contain further an inspiration contact terminal l-10 and an expiration contact terminal 13-20, respectively. The inspiration contact terminal I10 is connected through a conductor 31 to one fixed contact 32 of a reversible switch r1, the other fixed contact 33 of the switch r1, being connected by a conductor 34 to the expiration terminal contact 13-20. The movable contact of switch r-l connects contacts 32 and 33 alternatively to a common contact 35 of an alternator switch 36 which is moved back and forth between its two positions by driving means, not shown, at a frequency of between about 10 and times per second. The frequency of the alternator switch movements may be adjustable in known manner. During each of its cycles, the alternator switch alternately connects one side of a variable condenser 37 to the positive pole of a source of current which, in the example shown, provides a voltage of +300. The opposite side of the condenser 37 is connected to the zero terminal of the source of current.

The two electrode circuits are completed by two pairs of terminals 13, 14 and 23, 24 which can be attached to the body of a patient, for instance, in the manner illustrated in Figures 4 and 5. In these figures the electrodes 13 and 14 are illustrated by way of example only, as conducting belt portions 156 and 151 connected in front and in back by insulating members 152 and 153 and having each a lead 13a, 14a terminating in plugs 13b, 14b; re-

Patented J an." 28, 1958.

spectively. The opposite ends of the leads 13a and 140 may be attached to the belt portions 150 and 151 by contact fasteners 158 and 159. The electrode belts 150 and 151 may be attached to the body of a patient, for instance, directly above the diaphragm, in the manner shown so that, upon connection of the plugs 13b and 14b to the opposite terminals of an electrode circuit, current pulses will fiow through the diaphragm-controlling muscles in a direction substantially transversely or across the body of the patient. As will be seen in Figure l, the lead 13a is connected to the terminal N- and the lead 14a is connected to the terminal I-10.

The electrodes 23 and 24 may be, for instance, continuous belt elements 154 and 155 reaching partially around the body of the patient and being secured in front and back by insulating members 156 and 157. The electrode belt portion 154 has a lead 23a terminating in a plug 23b and the electrode belt portion 155 has a lead 24a terminating in a plug 24b. The electrode belt portions 154 and 155 have contact fasteners 160 and 161 by means of which they may be snapped or secured to the leads 23a and 24a.

As shown in Figure 4, the expiratory electrode belt composed of the electrode belt portions 154 and 155 is arranged about the body of the patient in the area of the lower abdomen, preferably just below the navel. When the electrode leads 23a and 24a are connected to the positive and negative terminals of an electrode circuit, current flows across the body in the area of the lower abdomen between the electrode belt portions 154 and 155.

Referring to Figure 6, it will be observed that the inspiratory and expiratory electrode belt portions 150, 151 and 154, 155 may be composed of a fiat metal conductor 162 provided with a jacket or cover of cloth or other absorbent material 163. Before applying the inspiratory and expiratory electrode belts to the body, the conductive electrode belt portions 150, 151 and 154, 155 are preferably moistened so as to increase the electrical conductivity through the underlying skin areas and produce a sufiicient transfer of low frequency electrical pulses across the body from the positive electrode 150 to the negative electrode 151, for example, to stimulate the underlying deep-seated muscle groups and produce a sufficient contraction to initiate inspiration and intake of air into the lungs.

The preferred locations of the inspiratory and expiratory electrode belt sections relative to the rib cage and navel, diagrammatically illustrated, are shown in Figures 4 and 5.

As indicated in Figure 1, the lead 23a of the expiratory electrode belt is connected to the terminal N- of electrode circuit 20 while the lead 24a of the inspiratory electrode belt is connected to the contact terminal E-20 of electrode circuit 20.

The flow of current in each of the electrode circuits 10 and 20 is determined by the charge on the grids of valves 11 and 21, which in turn is controlled by two separate grid control circuits 40 and 50. Each grid control circuit has input terminals 41, 51, respectively, these input terminals being alternate fixed contacts of a reversible switch r2. Each grid control circuit further comprises a rheostat 42, 52 having its opposite ends connected respectively to the associated input terminal 41, 51 of its circuit and to a common negative potential, which in the example shown is indicated as being 20 volts. The adjustable contacts of the rheostats 42 and 52 are connected in parallel to the common zero conductor each over a second adjustable rheostat 43, 53 and a condenser 44, 54. The adjustable rheostats 43, 53 form with the associated condensers 44, 54 time constant elements which permit an adjustment of the surge rate of the current pulses passed through the valves 11 and 21. The grids of the valves are connected to the control circuits and 50 between the adjustable rheostats 43, 53 and the condenser-s 44, 54,-respectively.

The movable contact of the reversible switch r-2 is connected to the zero conductor 30 over a make and break switch s-1 operating over contact 51a. A manually operated bridging switch b, shown in Figure 1 in open position, makes it possible to inter-connect grid control circuits and 50 for simultaneous operation.

The timing of the pulses supplied to the electrode circuits 10 and 20 for regulating the breathing rhythm, .is controlled by a timing device, the circuits of which are illustrated diagrammatically in Figures 2 and 4. This timing device comprises an inspiration control circuit 60, an expiration control circuit 70, and three two-position relays S, R, C. Relay S controls the contact s-1 in the grid control circuit and a contact s-2 of the timing device. Relay R controls contact r-1 of the reversible switch for the electrode circuits and contact r-2 of the grid control circuits, and relay C controls contact 0-1 of the timing device. The relays R and C have each one winding 61 and 62, respectively, in series with the inspiration control circuit 60, and one Winding 71 and 72, respectively, in series with the expiration control circuit 70. The relays R and C thus operate to shift their associated contacts to one position when curent flows in the inspiration control circuit 60 and to the opposite position when current flows in the expiration control circuit 70. The. relay S also has one winding 63 in series with the inspiration circuit 60 and one winding 73 in series with the expiration circuit 70, but this relay shifts its associated contacts to the same position whenever current flows in either the inspiration circuit or the expiration circuit. In order to shift the contacts associated with relay S to their opposite positions, this relay is provided with a third winding 81 in a pulse terminating circuit 80. Each of the circuits 60, 70 and contains further a glow lamp, 64, 74 and 82, respectively.

Associated with the inspiration and expiration control circuits 60 and 70, respectively, are inspiration and expiration starting circuits and 100, respectively, each including an adjustable rheostat 91, 101. The rheostats 9 1, 101 have movable contacts connected in parallel over a common lead and a master switch 111 to the positive terminal of a source of current. The winding of each adjustable rheostat 91, 101 is connected to one side of a condenser 92, 102, respectively. The other side of which 18 connected to the negative terminal of the source of current. Each condenser can be short circuited over a contact 93, 103, respectively, by means of the change-over sw tch 0-1 which is controlled by the relay C. The switch c-1 acts as a reversing switch to direct the current alternately to the windings 63, 61, 62 and 73, 71, 72 controlling the relays S, R and C. Referring to Figure 1, it be seen that in one position the relay R throws switches r-1 and r-2 to the expiratory electrodes 23, 24 and then the inspiratory electrodes 13, 14. Associated with the pulse-terminating circuit 80 is a starting circuit which comprises an adjustable rheostat 121, contacts 122 and 122a of the two-position switch s-2 controlledby the relay S and ,a condenser 123, one side of which is connected in one position to the movable contact of switch s-2 over rheostat 121 to conductor 110 while its other side'is connected to the negative terminal of the source of current. It should be noted that the inspiration control circuit 60 is connected across the condenser 92, the expiration control circuit 70 is connected across the condenser 102, and the pulse-terminating circuit is connected across the condenser 123.

A manually operable switch 65 permits temporary closing of the inspiration circuit at will.

' The arrangement of the inspiratory and expiratory electrode circuits and the timing mechanism which regulates the breathing rhythm are shown as part of my application Serial No. 231,417. Other arrangements are easily employed including a single electrode circuit with switching mechanism to alternately supply thelowv frequency current pulses to the inspiratory and expiratory electrode belt sections as will be readily understood.

With the electrode belt sections 150, 151 and 154, 155 attached to the body of the patient, for instance, as shown in Figures 4 and 5 and connected to the terminals of the electrode circuits, as shown in solid lines in Figure l, and switch b open, the apparatus operates in the following manner:

When the master switch 111 is closed, a charge is placed on the condenser 92 of the inspiration starting circuit 90 over the adjustable rheostat 91. After a time interval, which depends on the position of the movable contact of the rheostat 91, and which may vary from between about to about of a minute, the charge of the condenser becomes sufiicient to cause its discharge through glow lamp 64 and windings 63, 61 and 62 of relays S, R and C. This causes closing of switch s-1 and shifting of the movable contact of switch r-2 to the input terminal 41 of the grid control circuit 40. Simultaneously, the movable contact of switch r-1 is switched over to contact 32 to prepare a circuit through terminal L163. Closing of switch s-l and shifting of switch r-2 to input terminal 41 lowers the negative bias from the grid of tube 11 and induces a current surge through the plate circuit of said tube and the electrode circuit 19. The alternator contact 36 in its lower position places a charge on condenser 37 and in its upper position, in which it touches contact 35, permits a discharge of condenser 37 and the delivery of a short current impulse into the electrode circuit 141 through the valve 11, the indicator 12, the terminal N-10, lead 13a, electrode inspiratory belt section 151B transversely through the diaphragm muscles of patient, electrode belt section 151, lead 14a, terminal I-Il), movable contact of switch r-1 and alternator contact 36. By adjustment of the alternator frequency, the frequency of the impulses thus delivered can be varied from about to 150 times per second. An impulse frequency of about 50 to 60 per second has been found to be most favorable for many cases and a non-adjustable alternator operating in this range of frequencies may be used instead of the adjustable alternator shown. The alternator 35, 36 constitutes a source of low frequency current.

The duration of the individual impulses, on the other hand, can be changed independently of the frequency by adjustment of the. variable condenser 37. The proper selection of the duration of the individual short impulses is of considerable importance. The shorter the impulses are the smaller is the mean value of the current passing through the body with a corresponding diminution of possible undesirable side effects, such as a skin irritation and pain sensations. Generally, excellent results can be obtained with very short impulses of less than 1 msec. duration, which obviate skin irritations and pain sensations completely. In some cases, however, an effective muscle contraction can be obtained only with impulses of greater duration. In these cases, however, the sensitivity is usually reduced to such as extent that even relatively long impulses do not create any painful sensations.

The amplitude of the current impulses depends on the adjustment of rheostat 42. Adjustment of the rheostat 43 which forms part of the time-constant element 43, 44 makes it possible to effect a gradual increase in the amplitude of the successive current impulses of which each individual pulse is composed so that the current flowing through the electrodes and the muscles of the patient can be given the desired surge characteristics.

When current is supplied to the inspiration control circuit, change-over switch c-1 is switched from contact 103 to contact 93. This connects both sides of condenser 92 to the negative terminal of the source of current to insure a complete discharge of this condenser and to render recharging thereof impossible as long as switch c1 retains its upper position.

Simultaneously, the short circuit across condenser 1112 over contact 103 is broken and a charge is placed on condenser 102 over adjustable rheostat 101. The condenser 102 is now charged for a predetermined time interval determined by the position of the adjustable contact of rheostat 101.

Furthermore, when switch s-1 is closed, the movable contact of switch s-2 is shifted from its lower position to its upper position (see Figure 2) to close the circuit 121 thereby placing a charge on the condenser 123 over master switch 111, adjustable rheostat 121 and contact 122. By adjustment of the rheostat 121, charging of the condenser 123 may be completed in a time period which is less than that required for charging of the condenser 102, in order to cause termination of the current pulse stimulating the inspiration-controlling muscles prior to the beginning of the expiration phase.

When condenser 123 has received a sufficient charge, it discharges over the pulse terminating circuit through glow lamp 82 and winding 81 of relay S. This causes opening of switch s-1 with termination of the inspiration pulse and return of switch s-2 to its lower position to insure complete discharge of condenser 123. Thus, it is possible to slow down the breathing rhythm to increase, for instance, the time interval between the beginning of each inspiration phase and the beginning of the next following expiration phase, by adjustment of condenser 101, without increase in the duration of the inspiration current pulse which might cause undesirably long muscle contractions. The charging of condenser 192 is meanwhile continued, and when this condenser has attained its full charge, it discharges through the expiration control circuit 71), including glow lamp 74 and windings 71, 72 and 73 of relays R, C and S, respectively. As a result, switch s-1 is closed again and switch s-2 is returned to its upper position to close the charging circuit for condenser 123. Switches r-1, r2 and 0-1 are reversed, thus closing the grid circuit 51 for the grid of tube 21 over rheostat 52 and time-constant elements 53, 5'4, and also the electrode circuit 20 from one side of the condenser 37 over valve 21, indicator 22, contact N-Zi lead 230, anode 154 across the body through expiratory muscle groups of the patient, electrode 155, lead 24a, terminal E-Zfi, contact 33, movable contact of switch r1 in its right-hand position, contact 35 and alternator contact 36 to the other side of condenser 37. A current pulse of desired duration and characteristics is thus supplied to the expiratory muscles.

Due to the return of switch 0-1 to its lower position, the inspiration starting circuit 90 across condenser 92 is new again rendered operative and a new breathing cycle is initiated in the manner described before.

If it is desired to interfere momentarily with the automatic operation of the timer in order to start immediately a new inspiration phase, the physician or the patient himself my close switch 65, for instance, by operation of a push button, to short circuit glow lamp 64 and to obtain a flow of current in the inspiration control circuit through rheostat 91 and windings 61, 62 and 63 of relays R, C, and S. This shifts all the switches to their position for the start of an inspiration phase and causes the immediate passing of a current pulse through the inspiration controlling muscle group. When the push button is released, switch 65 opens and the timer resumes its automatic operation.

In the alternative arrangement of electrodes shown in Figure 5, the electrode belt sections 150, 151, and 154, 155 are arranged to transmit current pulses transversely of the trunk of the body in breathing rhythm from front to back rather than from one side of the body to the other as in the arrangement illustrated in connection with Figure 4.

It should be understood that the invention is not meant to be limited to the embodiments illustrated and described herein. The electrodes and the means for attaching them to the body of a patient may obviously be varied as desired, and they may be suitably attached in various positions to the body of a patient to effect alternating stimulation of inspiratory and expiratory muscle groups, including others than those specifically mentioned in the preceding specification, as may be desired. Other modifications and variations of the method and the apparatus of the present invention will occur readily to those skilled in the art without deviation from the principles and from the scope of the present invention, as defined in the following claims.

I claim:

1. A method for producing respiration which comprises applying positive and negative inspiratory electrode belt sections of substantial surface area to opposite sides of the body in the area of the diaphragm and passing low frequency current pulses across the body between said inspiratory electrodes to induce inhalation, at the same time applying positive and negative expiratory electrode belt sections at opposite sides of the body in the area of the lower abdomen and passing low frequency current pulses across the body between said expiratory electrodes to produce exhalation and alternately applying current to the respective inspiratory and expiratory electrodes in a breathing rhythm.

2. A device for producing respiration which comprises a pair of positive and negative inspiratory electrodes, said electrodes being in the form of extended belt sections of substantial surface area spaced apart but joined by insulating sections so as to be positioned on opposite sides of the body in the area of the diaphragm, a pair of positive and negative expiratory electrodes, said electrodes being in the form of extended belt sections of substantial surface area spaced apart but joined by insulating sections so as to be positioned on opposite sides of the body in the area of the lower abdomen, a source of low frequency current pulses, switching means in circuit between the current source of the electrodes and arranged to alternately connect the current source with the inspiratory and expiratory pairs of electrodes, said switching means being adapted to control the rate of switching such that it will change the flow of current back and forth between the inspiratory and expiratory electrodes in normal breathing rhythm.

3. A device for producing respiration comprising positive and negative inspiratory electrodes spaced apart but joined by insulating sections and arranged to be applied to the body as in the form of a belt on opposite sides of inspiratory muscle groups, positive and negative expiratory electrodes spaced apart but joined by insulating sections and arranged to be applied to the body as in the form of a belt on opposite sides of expiratory muscle groups, a source of current pulses and means connected between the electrodes and the current source applying said current pulses alternately to the inspiratory and expiratory pairs of electrodes in normal breathing rhythm.

4. A device for producing respiration comprising positive and negative inspiratory electrodes spaced apart in series and arranged to be applied to the body as in the form of a belt on opposite sides of inspiratory muscle groups, positive and negative expiratory electrodes connected together in series and arranged to be applied to the body as in the form of a belt on opposite sides of expiratory muscle groups, a source of current pulses, and switching means for directing said current pulses alternately to the inspiratory and the expiratory controlling electrodes in normal breathing rhythm, means for varying the amplitude of the current pulses to the inspiratory electrodes and means for varying the amplitude of the current pulses to the expiratory electrodes.

5. A device for producing respiration comprising positive and negative inspiratory electrodes spaced apart in series and arranged to be applied to the body as in the form of a belt on opposite sides of inspiratory muscle groups, positive and negative expiratory electrodes connected together in series and arranged to be applied to the body as in the form of a belt on opposite sides of expiratory muscle groups, a source of current pulses, and switching means for directing said current pulses alternately to the inspiratory and the expiratory controlling electrodes in normal breathing rhythm, means for adjusting the duration of current pulses to the inspiratory electrodes and means for adjusting the duration of the current pulses passed to the expiratory electrodes.

References Cited in the file of this patent UNITED STATES PATENTS 1,338,269 Wappler Apr. 27, 1920 -1,693,734 Waggoner Dec. 4, 1928 1,752,632 De Beaumont et al. Apr. 1, 1930 2,668,540 Browner .Feb. 9, 1954 

